Luck is about the individual, on a larger scale it's all about probability, and when you have millions of spins and thousands of users it's as usual pure math, wat might look like luck to you it's just a possibility coming true, nothing else.
Casinos don't care about individuals and their one game, what they really care and base their business model on is the whole sum at the end of the day, one or a hundred might get lucky and double or even triple their bankroll but a lot of other users who lose will compensate for that.

Also, losing 10 or 20 times in a row is nothing special, there have been cases of real-life roulette ending only black or only red for thirty times in a row!